1. Field of the Invention
The present invention relates to a spin injection magnetization reversal type magnetic random access memory (MRAM).
2. Description of the Related Art
Recently, a spin injection magnetization reversal type magnetic random access memory (e.g., non-patent reference 1) is proposed as a magnetic random access memory (MRAM). A cell of this magnetic random access memory comprises an MTJ (Magnetic Tunnel Junction) element and switching transistor. In a write operation using the spin injection magnetization reversing technique, an electric current is supplied perpendicularly to the film surface of the MTJ element, and the magnetization direction in a recording layer is changed by the direction of this electric current.
Unfortunately, the reversing current threshold value sometimes varies from one MTJ element to another, and the write characteristics deteriorate in this case.
[Non-patent Reference 1] IEDM2005 Technical Digest p. 473-476 “A Novel Nonvolatile Memory with Spin Torque Transfer Magnetization Switching: Spin-RAM” or J. of Magn. Magn. Mater., 159, L1 (1996) “Current-driven excitation of magnetic multilayers”